Floating Large Lump in Scrotum, Traveling in Groin & Scrotal Sac near Testicles

[Anastatia]

Floating 2-Inch Lump in Scrotum.

My boyfriend, age 31, has a large growth/lump in his scrotum. The lump is about 2 inches. When there is sexual activity involved, the lump moves around on his right side, traveling upwards through the scrotum, up the groin towards his penis. When the lump moves up into his groin area, he pushes the lump down, to move back into his scrotum toward his testicles. Sometimes he has to keep his hands and fingers pressed down on both, left and right, sides of his groin in attempts to keep the lump in the scrotal sac.

Particularly when he is leading up to an orgasm, the enlarged lump does not want to stay in his scrotal sac and continuously fights to be in his groin.

I believe, when the lump is in the groin region he cannot ejaculate. Which is one of the reason's he has to push the lump back down into his scrotum, towards his testicles.

What could this be?

He has several lumps on his body, including his rib cage/chest area. I asked him about the lumps sticking out of his upper body; he called them "growths". The doctor told him they are not cancerous, they are just "growths" he said.

When I tried asking about the 2-inch "growth" floating around his genitals he responded:
"That's what makes it feel good." - He said.

He has had this lump for at least 3 years, probably more.

I am very concerned.  

What could a 2-inch lump, moving around the male's genital area be? Could this be a Tumor?

Thank You.